1. Field of the Invention
This invention relates to a lens for a lighting fixture, and particularly, to a lens for a lighting fixture used, for example, for an overhead dome light for vehicles.
2. Description of the Related Art
A lens for a lighting fixture used for an overhead dome light for vehicles, has an engaging portion 12 (FIG. 7) with an engaging pawl 13 so as to be firmly fixed to a panel 15 when it is fitted thereto. The lens, further, has a plurality of pyramids formed on the back surface 11 thereof as shown in FIG. 6 on an enlarged scale so as to diffuse light creating an aesthetic feeling when the lighting fixture is seen by passengers. Further, a rib 2 is formed surrounding the back surface 11 of the lens. A top end surface 7 of the rib 2 is formed with a surface relief as illustrated in FIG. 7 on an enlarged scale so as to produce an aesthetic feeling by diffusing light like the above pyramids. A top end surface 14 of the engaging portion 12, also has a surface relief substantially parallel with the top end surface 7 of the rib 2.
When the vicinity of the engaging portion 12 is seen from a direction substantially perpendicular to the surface of the lens as represented by position α in FIG. 8, the surface relief appears to have continuity and beauty. When seen aslant as represented by position β, however, the surface relief appears irregular as represented by viewing line X which mars the appearance.